In the past few years, efforts have been concentrated on developing chemicals that will be highly effective against microorganisms when highly diluted, will be low in toxicity to humans and other animals, and will not injure the environment. Of the known disinfectants and antimicrobials, hydrogen peroxide appears to have exceptional potential, especially in terms of toxicity and injury to the environment, because the decomposition products, water and oxygen, are benign. Also, it tends to have broad spectrum antimicrobial activity. Broad spectrum activity is important in situations where harmful organisms are present but their identity is not known. Hydrogen peroxide based disinfectants are useful in many different applications, including in hospitals, clinics, laboratories, dental offices, home care and chronic care facilities. They may also be used in food and beverage processing and preparation, animal husbandry, the hospitality industry and for general sanitation, e.g. janitorial services.
In order to provide fast, effective action, prior art disinfectant solutions have had to employ relatively high concentrations of hydrogen peroxide. At higher concentrations, the solutions may not be practical or economically viable, may be subject to hazardous goods regulations, and may require special precautions for handling and use. For example, at concentrations of above about 8 w/w % aqueous solution, hydrogen peroxide is considered corrosive, more so at higher concentrations, and is also a strong oxidizing agent. Solutions containing less than about 8 w/w % hydrogen peroxide are preferred for their improved safety profile. At concentrations of 1-3 w/w % aqueous solution, hydrogen peroxide is considered non-corrosive and non-irritating; at concentrations of 3-7 w/w % aqueous solution, hydrogen peroxide is considered non-corrosive but an eye irritant.
Heretofore, one of the major drawbacks of hydrogen peroxide, in very low concentrations, is that its antimicrobial action is too slow. For example, prior art references indicate that a 0.1 w/w % aqueous solution of hydrogen peroxide requires 60 minutes to disinfect surfaces contaminated with staphylococcus aureus, whereas a 25.8 w/w % aqueous solution of hydrogen peroxide requires only 20 seconds. The latter solution is clearly unacceptable from both commercial and economic standpoints.
Attempts have been made to improve the efficacy of low concentration hydrogen peroxide disinfecting solutions. For example, Winterton et al. discloses, in U.S. Pat. No. 5,523,012, a hydrogen peroxide disinfecting solution for contact lenses buffered to a pH of about 6.9 and which has from about 0.1 w/w % to about 1.0 w/w % of an ocularly compatible surfactant. In one experiment, the addition of about 0.4% anionic sulfosuccinate surfactant improved the killing time for aspergillus fumigatus to 6.9 minutes, compared to 12.3 minutes for a solution containing no added surfactant. However, even 6.9 minutes is far too long for many applications.
U.S. Pat. No. 5,264,229 to Mannig et al teaches a process of extending the shelf life of commercially processed food products, such as poultry, fowl and seafood products by contacting the food products with a sufficient amount of food grade hydrogen peroxide and food grade surface active agent selected from the group consisting of alkyl aryl sulfonates, sulfates, sulfonates of fatty acids, sulfates of alcohols and sulfosuccinates. The hydrogen peroxide and surface active agent are present in chiller water in which the food products are immersed and serve to remove and reduce the number of bacteria on the surface of the food products. Up to 1 w/w % hydrogen peroxide and from 5 to 100 ppm surface active agent are used in the chiller water. The solutions of Mannig et al are able to achieve only moderate levels of disinfectant activity using a 45 minute contact time. While the Mannig solution may be sufficient for preserving foods, it is inadequate for short contact time disinfection.
Hydrogen peroxide is a compound which is highly susceptible to decomposition by the presence of dissolved impurities, mostly transition metal cations. Impurities causing hydrogen peroxide decomposition are typically contained in either the water used in preparation of a commercial disinfectant from an aqueous hydrogen peroxide stock, or in the additional ingredients of the formulation (i.e. surfactants, builders, etc.). The most effective method for preventing decomposition of the hydrogen peroxide is by sequestration or chelation of the dissolved catalytic metal species, typically through the use of phosphate or phosphonate compounds. The increased product shelf life gained by the use of phosphorus stabilizers has allowed the commercial, albeit limited, use of such compositions.
Most if not all peroxygen-based mixtures used for cleaning and disinfection discussed in the prior art either suffer from impracticably long contact times, unfeasibly high hydrogen peroxide concentrations or contain at least one type of phosphorus compound in non-trace quantities. Although the role of phosphorus in the eutrophication of lakes and rivers due to artificial sources is still a matter of debate, many regions in the world have imposed severe restrictions on the amount of phosphorus that can be discharged into storm and sanitary sewers.
In certain situations, it is therefore desirable to provide a complex multicomponent hydrogen peroxide solution with the capability of disinfection at short contact times, has low non-hazardous concentrations of ingredients, and which contains no phosphorus-based materials.
Though the prior art is replete with hydrogen peroxide containing disinfectants, the present invention is intended to provide an improved hydrogen peroxide disinfectant having enhanced activity to permit rapid and effective disinfection of hard surfaces and skin of humans and animals with a hydrogen peroxide concentration as low as 0.5 w/w %. Select embodiments of the present invention do not contain any added phosphorus-based materials other than those naturally present in commercial hydrogen peroxide stock solutions, which are present in quantities permitted in jurisdictions which impose restrictions on phosphorus discharge into the environment.